Hence, soluble HLA-G may be perceived as a new negative regulator for the EPO receptor signaling and may therefore represent a potential therapeutic agent for the treatment of patients carrying the mutation JAK2 V617F found not only in polycythaemia vera but also in the other two main myeloproliferative syndromes, essential thrombocythemia and idiopathic myelofibrosis. This evidence concerns the gene HLA-G and acquired polycythemia vera.